Coronary artery disease is a common ailment that affects millions of people. Coronary artery disease may cause the blood vessels providing blood to the heart to develop lesions, such as a stenosis (abnormal narrowing of a blood vessel). As a result, blood flow to the heart may be restricted. A patient suffering from coronary artery disease may experience chest pain, referred to as chronic stable angina during physical exertion or unstable angina when the patient is at rest. A more severe manifestation of disease may lead to myocardial infarction, or heart attack. Significant strides have been made in the treatment of coronary artery disease including both medical therapy (e.g. statins) or surgical alternatives (e.g., percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG)). Invasive assessments are commonly used to assess the type of treatment a patient may receive. However, indirect or noninvasive assessments for formulating a patient treatment are being explored and developed.
Heart disease is typically viewed as resulting from vessel disease, in particular, narrowing or blockage inside vessel lumens in a way that impacts blood flow. Currently, treatment assessment takes into account such intraluminal factors. Meanwhile, vessel size, itself, may also fluctuate. For example, healthy vessels may change size in response to various physiological states in a manner that differs from that of a diseased vessel. The discrepancy in response between healthy vessels and diseased vessels may serve as an indicator of the severity of a disease. Thus, a desire exists for understanding how severity of cardiovascular disease may be inferred from changes in vessel size in response to different physiological states. Furthermore, a desire exists to improve treatment of cardiovascular disease by better assessing the severity of cardiovascular disease.
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